Physician Assistant - Medical. Assesses, plans and provides patient care under the supervision of a physician. Examines patient, performs comprehensive physical examinations, and compiles patient medical data, including health history and results of physical examination. May require a master's degree and must be a graduate of an accredited physician assistant program.
How much land does it take to support a human being? Boundaries of China superimposed upon those of the USA. Let's do the math again, but this time for the entire planet. The total land surface area of Earth is about 57,308,738 square miles, of which about 33% is desert and about 24% is mountainous. Subtracting this uninhabitable 57% (32,665,981 mi2) from the total land area leaves 24,642,757 square miles or 15.77 billion acres of habitable land.
However, some estimate only about 18.5 million km2 are inhabitable by humans because high mountains, deserts, ice, etc. cover the rest. So, only about 18.5 trillion people would fit, assuming one square meter (m2) per person. Now, if we give everyone a little more room (say 1/2 acre to grow food), then that would allow for about 9 billion people. (1 acre = about 4,047 square meters. 1/2 acre = 21,780 ft2 or a square plot of about 147 ft on the sides.) Earth's population just surpassed 7 billion in 2011. It is estimated we will reach 9 billion by 2046. Some would argue the earth is just about full. And sustainability is another issue. Assuming we are talking about land surface (not water), the earth has about 148,940,000 square kilometers. So, it could hold slightly less than 149 trillion people, if they each had their own square meter of ground. (148,940,000 km2 = 148,940,000,000,000 m2.)